london



Nov. 2, 1926. 1,605,818

A. MCD. DUCKHAM PROCESS OF HEATING GOODS AND ANNULAR FURNACE OR KILN USED THEREFOR Filed Dec. 18, 1925 3 Sheets-Sheet .l.

Nov. 2 1926.

A. M D. DUCKHAM PROCESS OF HEATING GOODS AND ANNULAR FURNACE 0R KILN USED THEREFOR File nec. 18; 1923 Sheets-Sheet 2 FIIIIII H IL| Nov. 2 1926. 1,605,31$

A. M D. DUCKHAM PROCESS OF HEATING GOODS AND ANNULKAR FURNACE OR KILN USED THEREFOP 18, 1923 3 Sheets-Sheet 3 Fie 037%W77/3 ogall mivwz Patented Nov. 2, 1926.

UNITED STATES PATENT OFFICE.

ARTHUR MODOUGALL IDUGKHAM, OF LONDON, ENGLAND, ASSIGNOB TO 'WOODALL, DUCKHAM & J ONES (1920) LIMITED, OF LONDON, ENGLAND, A BRITISH COMPANY,

PROCESS OF HEATING GOODS AND ANNUIJAR FURNACE OR KILN USED THEREFOR.

Application filed. December 18, 1823, Serial No This invention relates to annular tunnel furnaces or kilns of the t pe in which the goods, such as bricks, whic are to be heated are carried on a rotating annular support forming the floor of the furnace or kiln, and in which heating gases are admitted to travel in counter-current to the goods throu h one section of the annular tunnel, whi e the goods are cooled in another section by air moving, in the opposite direction, to the place of combustion. This invention also relates to the process of heating goods in the annular furnaces or kilns.

In such furnaces or kilns there is some difficulty in heating all the goods to the same temperature, those which are inside the stacks or piles being less heated than those which are on the outside.

This invention improves the construction, ,arrangement'of operation of such furnaces or kilns, mainly with a View to overcoming this defect.

According to the invention the stacking of the goods and the draught in the kiln are such that the combustion gases, which are hottest at the upper part of the tunnel are so distributed throughout the stack that the goods are all heated to substantially the same temperature.

The goods are stacked with interspaces which serve as fines for passage of the gases in circumferential direction in the kiln and such spaces are of size gradually increasing from top to bottom of the stack so that there is a correspondingly gradual decrease in the resistance to the passage of the gases in the said flues, whereby a larger proportion of the gases finds its way through the lower flues. For the same purpose the interspaces at the sides of the stack may be narrower than those at the middle part. The efiect may be enhanced by some form of frictional resistance or directing bafiles on the internal walls of the annular chamber.

The distribution thus-afforded is aided by drawing combustion gases downwards through the stacks by means of lateral ports duly spaced apart in the walls of the kiln and communicating with a flue. These ports being controlled by dampers, the down- 681,422, and in Great Britain February 2, 1923.

ward draught may be adjusted to suit the state of the goods passing each port or set of ports.

It is not essential that the whole stack of goods should have its interspaces graded in the manner described above, since it sufiices if this grading is observed at that vertical face of the stack which first meets the combustion gases.

For the purpose of preventing free passage of gases over the tops of the stacks, a seallng device is provided at suitable places between the goods and the roof of the tunnel; for instance each stack may carry a transverse layer of sand of suitable depth and the roof of the annular tunnel may be slightly inclined from the entrance to the exit so that the seal remains throughout the travel of the stack through the tunnel. Less advantageously the layers of sand may he strickled in known manner by partitions depending from the roof of the tunnel and of successively greater depth in the order in which the goods pass them.

In the accompanying drawings Fig. 1 is a sectional plan and Fig. 2 a developed vertical section of an annular kiln constructed in accordance with the invention. Fig. 3 is a part longitudinal vertical section drawn to an enlarged scale and Fig. 4: is a section on line H of Fig. 8. Figs. 5'and 6 are seciionslon lines 5-5 and 66 respectively of Fig. 7 is a cross section showing a modification of the invention and Fig. 8 is a part sectional plan showing a detail of construction in a modification.

As usual in such kilns the annular tunnel is interrupted at a part b where the goods to be burnt are loaded on the annular platform 0, where also those which have been burnt are unloaded. The platform has annular rails 01 on its under surface supported on wheels e carried by stationary radial axles. A motor 7 is geared to pinions g which drive an annular rack g on the under surface of the platform.

When the motor is started the stack of raw goods is carried into the tunnel through door a and a stack of burnt goods emerges from the tunnel through door a as is usual in such kilns.

Producer gas from a generator, not shown, enters at h and meets secondary air wh ch has been drawn through ports 11 near the mlet door aand numerous flues i constructed in the walls and roof of the kiln.

The products of combustion travel through the tunnel in the direction opposite to that of the travel of the goods and escape by the flues 7.: to the chimney stack is, where the draught may be aided by a fan The flue 70 on the inner side of the annulus and that on the outer side are under separate control by suitable dampers, in order that the proportion of heating gas travelling on the inner side to that'travelling on the outer side may be adjusted.

At suitable distances apart around the tunnel and on both sides of it, and preferably towards the bottom of it,- are ports Z suitably controlled 1) dampers and affording communication etween the lower part of the tunnel and flues Z in the sides of the tunnel, these fiues being connected with the main waste gas lines k. By controlling these ports the temperature of the goods in the various parts of the kiln can be'adjusted.

After passing the combustion zone about the orts it, the goods enter the cooling zone 0?. w ere they part with the greater portion of their heat to air drawn into flues 0 through ports 1; and travelling in the direction opposite to the travel of the goods. In the drawing it is assumed that the heated air leavesthe flues 0 at 0' where the device (not shown) for creating the necessary suction in the fines 0 draws the air through any apparatus, such as a drying floor, where its heat may be used. In some cases it is advantageous to connect the ports 0. by a diametrical flue with ports in the heating section of the tunnel, for instance on the dotted line then the draught in flues 0 becomes a part of the main draught of the kiln and the heated air entering the ports at a helps to dry the goods.

Referring to Figs. 3 and 4 it will be seen that at the rear end of each stack of goods 1' there is a row of trough-shaped bricks 8 carrying sand 2. Qwing to a slight inclination of the roof of the tunnel (say 1 in 7 00) the continued contact of this sand with the roof is ensured. The goods at that face of the stack which is forward in the direction of travel are spaced apart to an extent which gradually increases from the top to the bottom of the stack, as indicated at u. Furthermore, the interspaces at the sides of this face of the stack are narrower than those at the middle.

When the goods do not lend themselves to being stacked with regular interspaces, definite flues may be formed by stacking the goods in suitable manner. Such an arrangement is shown in the cross section Fig. 7, where 'v represents a flue provided in the stack.

Fig. 8 shows a modification in which the internal courses of the side walls of the heating section of the tunnel are built of projecting bricks m so that the heating gases are deflected towards the goods when passing between the stack and the wall.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I c1a1m:-

1. A process of heating goods in an annular kiln, which process consists in stacking the goods With interspaces which are in circumferential alignment with one another to form passages continuous throughout the length of the stack, causing combustion gases to travel through the aligned interspaces, and causing the stack to move continuously counter to the combustion gases.

2. A process of heating goods in an annular kiln, which process consists in stacking the goods with interspaces forming passages continuous throughout the length of the stack, the passages at the upper part and sides of the stack being adapted to offer more resistance to travel of combustion gases than the passages at the remaining parts otter, causing combustion gases to travel through the said passages, causing the stack to move continuously counter to the combustion gases, and causing a portion of such combustion gases to travel d0wnwards through the stack.

3. An annular kiln of the character described, comprising a main waste gas flue, a continuous flue in the outside wall of the annulus connected with the said main waste gas flue, said annulus having ports spaced around it and affording communication between the lower part' of the interior of the kiln and the said continuous flue, and means adapted to control each of the said ports.

4. An annular kiln of the kind herein referred to and havin the features referred to in claim 3, wherein the stacks of goods carry a layer of sealing material such as sand, and the roof of the tunnel is slightly inclined in the direction of travel of the goods so that the said layer is in contact with the roof throughout the travel of the stack.

5. An annular kiln of the character described, comprising a kiln chamber bounded by a roof and walls, said chamber having ports for the admission of combustion gases into same and flues for withdrawing the said gases, that part of the chamber which extends between the said ports and fiues constituting the heating section of the chamber, said heating section having numerous fiues in its walls and numerous flues in its roof, all of said. numerous fiues being open at' one formed between the inner wall of the kiln 10 and the stack on each side of the stack, said kiln having projections on its inner Walls adapted to deflect into the said passages gases passing long the said s aces,

In testimony whereof I ave signed my 15 name to this specification.

ARTHU McIDOUGAUL DUCKHMW. 

